Intake Leak / Emissions Test?

[Traian]

I think I have an intake leak again. I've had the CEL come up twice on startup and stay on for a couple of minutes, and last night the idle was rough at a stop light. It's the exact same thing i had last year, but then one throttle body gasket fixed it...sigh....

Anyway, I just received a notice to do my emissions test, and I was wondering how this would affect it? Do I have to get this fixed before I take the test? I'd rather not take it more than once - can't think of anything else that needs changing, the only emissions related thing on my car that's of an unknown vintage are the O2 sensors (well, and the cat) - everything else is almost new.

I figure, if anything, the car runs leaner so it should lower emissions. But what do I know... I'm going to get this fixed anyway, but I have to take the expenditures one at a time so I need to know which one to do first.

Thanks :)

[Chris'91'525i]

I think I have an intake leak again. I've had the CEL come up twice on startup and stay on for a couple of minutes, and last night the idle was rough at a stop light. It's the exact same thing i had last year, but then one throttle body gasket fixed it...sigh....

Anyway, I just received a notice to do my emissions test, and I was wondering how this would affect it?
Thanks :)

In Calif. a CEL is an automatic failure on emission testing.
I would try to fix that first, maybe do the 'stomp' test to pull some codes to narrow it down.

[Traian]

Thanks for the reply. The CEL is not always on. It just came on a couple of times on startup and went out after 2 min. Also, I've tried the stomp test before and it doesn't seem to work for me. It might be a US thing only - I am in Canada...

[bmw540]

Check the battery if it is fully charged. Suggest diconnect and charge over night and see if this resolves your issue.

I had a simular issue which was caused from the battery not having enough charge.

[Traian]

Thanks for the suggestion. The battery is pretty new and well, I got a lumpy idle sitting at a traffic light a couple of days ago, and since it was one of the coldest days yet this year, I'm leaning toward an itake leak. I hardly drive the car really, so when I get some time I'm gonna go get some carb cleaner or something and take the engine cover off and spray it around to confirm. But I really need to do this emissions test soon and get my new plates, so if I could do that first it would be great :)

Anyone know if I can?

[brosher]

I had the same symptoms as you and new intake gaskets and PCV plate cured the problem.

I posted my parts list and a link to the how to here:
http://www.bimmer.info/forum/showthread.php?t=26873

[BillionPa]

a car running lean will have lower hydrocarbon emissions, but a massive increase in nitrogen oxides.

do replace the ASC o-rings if you have ASC, and the o-rings along the itake tube, there are 2 i believe.

replace the PCV plate and gasket at the rear of the intake manifold if you havent done it, and change out the charcoal canister.

if you are unsure of the O2 sensors, get new ones. you may also want to look for some new spark plugs as idle running can foul them.

after all that crap is replaced and the car is running smooth, see if any local dealers to terraclean treatments, which is a high tech version of fuel system cleaning. 7oz of acetone in a full tank will also lower emissions.